Spherical plain bearing assemblies typically include a ball positioned for rotational movement in an outer race. The ball defines an outer surface, and the outer race defines an inner surface contoured to receive and retain the ball therein such that the outer surface of the ball is in sliding engagement with the inner surface of the outer race. Contamination of the sliding engagement surfaces, namely, the outer surface of the ball and the inner surface of the outer race, is one of the leading causes of bearing damage. Typically, the spherical plain bearing assembly includes a single sealing arrangement on opposing sides thereof, wherein a seal is provided in a single groove for retaining lubrication between the sliding engagement surfaces and for inhibiting the ingress of dirt, water, particulate matter, and other contaminants to the sliding engagement surfaces.
For example, a single spread lock type seal is positioned in each single groove positioned on opposing sides of a spherical bearing, as described in U.S. Pat. No. 6,626,575, the subject matter of which is incorporated herein by reference. Typically, a single groove on each of opposing sides of the spherical bearing was employed to minimize the axial dimensions of the bearing while maximizing the load bearing capability of and sliding engagement between, the outer surface of the ball and the inner surface of the outer race. Thus, use of more than one groove or seal per bearing side was not considered.
In addition, U.S. Pat. No. 9,157,480, the subject matter of which is incorporated herein by reference, discloses a bearing assembly having an external seal positioned in a first annular groove and an internal seal positioned in a second annular groove. The internal seal has an inner lip and an outer lip that are flexibly compressed. The internal seal is stiffer than the external seal, because of the compression.